The present invention relates generally to electronic displays for aircraft and more specifically to potential thrust indicator symbology in an aircraft cockpit display for displaying aircraft engine thrust (or engine power) in terms of actual and potential aircraft flight path.
Experienced aircraft pilots are familiar with aircraft handling qualities under normal flight conditions. Thrust, weight, lift, and drag are the forces that act upon an aircraft. Maneuvering is accomplished by variations of these forces and is controlled by the throttles and flight controls. The power produced by the engines determines the angle that an aircraft can fly and still maintain airspeed (e.g. neither accelerate nor decelerate). Similarly, the drag on the airplane determines the descent angle that the airplane can fly and not accelerate. Aircraft drag and engine thrust models are used to indicate engine thrust as a climb or descent angle on the display where the greatest climb and the greatest descent angle represents the maximum and minimum power parameters.
Electronic displays such as Primary Flight Displays (PFD""s), Head-Up Displays (HUD""s), Head-Down Displays (HDD""s) and the like are well known and widely used to display information in aircraft. FIG. 1 illustrates a conventional flight path vector group 10 presented to an aircraft pilot on an attitude display. The display shows a horizontal line 50, which indicates the axis of flight parallel to the horizon. Pitch ladder 60 indicates the pitch or potential pitch of the plane. A flight path vector (FPV) indicator 20 represents the sum of all forces acting on the aircraft and indicates the direction of aircraft translation through space. A speed error indicator 30 emanates from the FPV indicator 20 and represents the difference between the selected airspeed and the current airspeed. The potential flight path vector (PFPV) indicator 40 is displayed in reference to the FPV indicator 20. PFPV indicator 40 is an indication of the aircraft""s instantaneous acceleration along the flight path. The angle at which the PFPV indicator 40 is displayed relative to the pitch ladder represents the acceleration scaled by the acceleration due to gravity. The FPV indicator 20 and the PFPV indicator 40 may be obtained from onboard inertial reference systems, Global Positioning System (GPS) aided attitude sensors, or the like. In FIG. 1, the display indicates that the aircraft is accelerating (the PFPV indicator 40 is above FPV indicator 20). Further, PFPV indicator 40 indicates that the flight path may be increased to approximately a 6-degree climb with no acceleration along the flight path.
However, with the prior art displays as described above, the pilot is given no direct indication of thrust. Rather, the pilot must utilize some internal model (usually gained through experience) based on the existing engine displays. Thus, there exists a need for an aircraft display which not only provides the pilot with a means for directly setting engine power to achieve desired performance, but also enables precise aircraft speed control with a reduction in pilot workload and provides control symbology in the pilot""s primary field of view.
Various aspects of the present invention provide an aircraft display apparatus which combines a flight path vector group with a potential thrust indicator to reduce pilot workload. The display apparatus includes a display screen, a pitch ladder symbol displayed on the screen, a horizontal line (representing level flight) displayed on the screen and a flight path vector group displayed on the screen. The flight path vector group includes a flight path vector symbol, a potential flight path vector symbol, a potential thrust symbol, and a speed error indicator. The flight path vector group is oriented on the display screen in relation to the pitch ladder and the horizontal line. The position of the potential thrust symbol is relative to the pitch ladder and represents current engine power and power limits of the aircraft.
In accordance with another embodiment of the present invention, the potential thrust symbol further comprises a thrust and drag limit symbol and at least one throttle symbol.
In accordance with yet another embodiment of the present invention, the potential thrust symbol indicates the aircraft""s climb capability with a failed engine.
In accordance with a further embodiment of the present invention, the potential thrust symbol indicates the potential aircraft descent angle when drag devices such as speed brakes, flaps and landing gear are activated.
These and other aspects of the present invention are described in the following description, attached drawings and claims.